The use of EGR as an addition to charge air introduced into the engine cylinders aids in controlling tailpipe emissions, especially NOx and particulates.
Because a diesel engine that powers a motor vehicle runs at different speeds and loads depending on various inputs to both the vehicle and the engine that influence engine operation, the nature of the charges created in the cylinders change as engine speed and load change. Exhaust gas recirculation requirements also change with engine speed and load changes.
A processor in an engine control system processes data indicative of parameters such as engine speed and engine load to develop control data for controlling constituents of the charges. The data developed is used to control turbocharger boost, engine fueling, and EGR rate.
Alternative combustion processes for a compression ignition engine can provide significant reductions in tailpipe emissions, NOx (oxides of nitrogen) and DPM (diesel particulate matter). Examples of alternative combustion processes include Homogeneous Charge Compression Ignition (HCCI), Controlled Auto-Ignition (CAI), Dilution Controlled Combustion Systems (DCCS), and Highly Premixed Combustion Systems (HPCS).